gdm3 - GNOME Display Manager

Author

       Martin Kasper Petersen <mkp@SunSITE.auc.dk>

       This  manual  page  written by Steve Haslam <araqnid@debian.org> for Debian GNU/Linux. Updated by Raphaël
       Hertzog <hertzog@debian.org>, Ryan Murray <rmurray@debian.org>, Josselin  Mouette  <joss@debian.org>  and
       Vincent Lefevre <vincent@vinc17.net>.

GNOME 49~alpha.1-0ubuntu1                          2025-07-07                                          GDM3.8(8)

Description

gdm3 is the equivalent of xdm(1x) or wdm(1x), but uses the GNOME libraries to provide a GNOME look-and-
       feel. It provides the GNOME equivalent of a "login:" prompt.

       gdm3 reads /etc/gdm3/custom.conf for its configuration. For each local display, gdm starts an X server
       and runs a minimal GNOME session including a graphical greeter. If configured so, the main gdm process
       also listens for XDMCP requests from remote displays. These requests can either be direct, causing gdm3
       to start a session on the remote display, or indirect, causing a chooser to be opened.

       When managing a display, gdm3 attempts to execute /etc/gdm3/Init/display, or /etc/gdm3/Init/Default if
       that does not exist. When a user logs in, gdm3 first attempts /etc/gdm3/PreSession/display (or
       /etc/gdm3/PreSession/Default), and then one of the sessions defined in /usr/share/xsessions. When the
       session has completed, gdm attempts to run /etc/gdm3/PostSession/display, or
       /etc/gdm3/PostSession/Default.

       gdm3 maintains information about the displays it is managing in /var/lib/gdm3. This includes xauth
       information, so this directory is not readable to normal users.

       gdm3 uses PAM to perform authentication using the config file /etc/pam.d/gdm3.

Environment

       XAUTHORITY
           Upon  session  startup,  GDM  sets  the XAUTHORITY environment variable to a session-specific file in
           /run/gdm3.

           Applications and scripts that assume this file is set to ~/.Xauthority will not work. To  access  the
           display you need both DISPLAY and XAUTHORITY variables.